Design - BEng 2 - DSGN 215

Lecture 1

Below are some key points about design, many of these will be further discussed in future lectures.

Design is an iterative process - at various stages it will be necessary to go back and re - consider some decisions. However at some point an agreed 'freeze' date must be specified, after which no changes will be permitted. Otherwise project deadlines will not be met and costs will rise - often catastrophically.

The following are major steps in the design process:

Design problems are normally complex, even if they can be very simply stated, hence appropriate methodology needs to be understood and followed.

Almost invariably an important objective is to minimise time to market.

A serial approach has been traditionally used. Now simultaneous, or concurrent engineering is the standard, much more efficient approach.

Communicating any design accurately and economically is vital. This can be done by drawing, CAD, 2D, or Solid model data base - that can be shared (with appropriate access security) throughout the company and possibly with customers and suppliers.

The choice of manufacturing processes and materials must be considered to be an integral part of the design process.

Design problems are frequently multidisciplinary.

Some related important issues are:

Safety needs to be designed in at the outset.

Building in quality at the design stage is essential.

Quality must be owned by every level of the organisation.

A good understanding of the loads and operating conditions are essential.

Design review is an important part of the design process to monitor progress.

Analysis and simulation using sophisticated computer software are increasingly used to speed design while making the process more accurate.
Using modern software it is possible to carry out a range of 'studies' to assist in achieving an efficient, or optimum, design. For example:

Design Optimisation: Typically a component will be required to have a minimum mass while at the same time ensuring the maximum stress is below a specified value. The software can vary the sizes of features on a component while ensuring the specified conditions are met.
Sensitivity Study: The effect on varying a particular dimension on the maximum stress occurring in a component may be of interest. Software can investigate this helping to determine how important particular dimensions are.

Design for manufacture / assembly / maintainability, is becoming increasingly important as consumers become more sophisticated. Modular design is an important way of meeting these requirements.

References and Assignments - See details on separate sheets.

Return to Module Introduction.

David J Grieve, 9th March 2005.